In increasing measure, optical sensors or cameras, which are exposed to soiling by the atmosphere, will be used in larger numbers in future motor vehicles. Even today, camera systems that help the driver in maneuvering are installed in some vehicles, in particular in trucks and buses. Such exterior cameras, or the transparent covers that cover the cameras toward the outside, are subject to soiling by dirt particles and to degradation of optical performance by ice, frost and snow. Furthermore, sensors and cameras are impaired in their optical effectiveness by deposition of liquid, especially dew or rain. This problem of soiling, and of impairment of the optical transmittance of the transparent cover, also applies to optical sensors that monitor the roadway in front of the motor vehicle, for example, in order to influence automatic regulation of illumination distance in such a way that the roadway in front of the vehicle is illuminated optimally and blinding of oncoming vehicles is prevented.
In the case of such exposed transparent covers which cover optical sensors or optical cameras toward the outside as protection against the ambient atmosphere, the problem is therefore that they must be kept in a condition which insofar as possible does not impair their optical transparency toward the outside. To this end the exposed cover must be clean or must be kept clean, and it must in general also be dry. Consequently the object of the present invention is to keep exposed transparent covers of sensors and cameras clean or if necessary to free them of dirt when they are soiled, and to dry them or keep them dry.